Luminogenic Polyacetylenes and Conjugated Polyelectrolytes: Synthesis, Hybridization with Carbon Nanotubes, Aggregation-Induced Emission, Superamplification in Emission Quenching by Explosives, and Fluorescent Assay for Protein Quantitation

Phenylacetylene and 1-pentyne derivates containing aminated tetraphenylethene (TPE) units 1 and 2 are synthesized. The TPE-functionalized luminogens are nonemissive in dilute solutions but luminescent as solid aggregates, Showing H novel behavior of aggregation-induced emission (AIE). The monomers are polymerized to their corresponding polymers P1 and P2 with an E conformation by organorhodium catalysts, although Rh-catalyzed polymerizations normally yield Z-rich polyacetylenes. Whereas P1 fluoresces faintly in THF, its light emission is enhanced by aggregation inaqueous media, exhibiting an aggregation-induced emission enhancement (AIEE) effect. Oil the other hand, P2 is AIE active: the emission of its nanoaggregates Suspended in 90% aqueous mixture is similar to 57-fold stronger than that Of its Solution in THF. A novel superamplification effect is observed in the emission quenching of P2 nanoaggregates by picric acid (PA): the quenching constant (K-SV) is nonlinearly increased with the quencher concentration and reaches a very high value in the high [PA] region (K-SV similar to 350000 M-1). P1 and P2 are transformed to conjugated polyelectrolytes P1(+) and P2+ via ionization by hydrochloric acid. P1+ readily hybridizes with carbon nanotubes, affording functionalized P1+/nanotube hybrids with good water miscibility. Emission of P2+ in aqueous buffer is boosted when it binds to bovine serum albumin (BSA), allowing the polymer to work as a sensitive bioprobe for BSA quantitation at ultralow protein concentration (0-0.6 ppm).